Rotary piston pump



April 22, 1958 P. A. JEAN-MARIE GUINARD 2,831,438

ROTARY PISTON PUMP Filed Nov. 23, 1953 5 Sheets-Sheet 1 Flj92 Fl9:3

' IN VENTOR wow JEAN-Mm: Gill/MRO April 22, 1958 P. A. JEAN-MARIE GUINARD ROTARY PISTON PUMP 3 Sheets-Sheet 2 Filed Nov. 23, 1955 INVENTOR wriw-me/i film M0 'ATTORDNE April 1958 Q P. A. JEAN-MARIE GUINARD Q 2,831,438

ROTARY PISTON PUMP Filed Nov. 23, 1955 3 Sheets-Sheet 3 I NVEN TOR llvad/mrJiw-Mer 60/ 0 M ATTORN United States Patent ROTARY PISTON PUMP Paul Andr Jean-Marie Guinard, Saint-Cloud, France Application November 23, 1953, Serial 398,862

Claims priority, application France November 21, 1952 1 Claim. (Cl. 1031 61) The present invention relates to a rotary piston pump of the type including a fixed pump-barrel accommodating arotatable cylinder having two or several pairs of transverse bores, the bores of each pair intersecting each other at right angles, and each bore slidably accommodating a pair of opposed coupled pistons rotating around an axis offset with regard to the axis of the cylinder; the throw or eccentricity, during rotation of the cylinder, causing the pistons to reciprocate in their bores, the ends of which communicate successively with a suction port and with a delivery port arranged in the fixed pumpbarrel.

When pumps of this type are required to give a high discharge, the cylinder is constructed to include several pairs of crossed bores, offset at 45 with regard to each other, the cylinder being constituted by several longitudinal sections which are limited to the transverse symmetry planes of said crossed borings and are joined by means of bolts whilst the opposed pistons in each pair are made in a single U-shapedpiece including, in addition to the two pistons, a connecting side plate with. a passage-way for the shaft.

This mode of construction nevertheless offers serious drawbacks especially in the case of pumps having to work under a high head, as, on the one hand, the longitudinal screws or bolts used for the assembling of the successive sections of the rotating cylinder are subjected to high shearing stresses resulting from the torsional stresses suffered by these sections in relation to each other, and on the other hand as the U-shaped coupled pistons, because of their one-sided connection, tend to open under the pressure, giving rise to wear and lack of tightness.

The pump constructed according to the present invention aims at overcoming the above mentioned drawbacks by rendering impossible any detrimental deformation of the cylinder and of the assemblies of coupled pistons.

Therefore, the pump according to the invention includes a cylinder cast in one piece and pairs of opposed coupled pistons, the pistons of each pair being removably joined together by two lateral connecting pieces arranged on both sides of the axis of the pistons.

By way of example, several embodiments of the pump according to the invention are hereafter described and illustrated in the annexed drawings, wherein;

Figure 1 illustrates, in longitudinal cross-section, a rotary piston pump according to the invention including two sets of two pairs of coupled pistons,

Figure 2 is a transverse section on the line II-II of Figure 1,

Figure 3 is a side elevation of a pair of coupled pistons with their connecting means, as used in the pump of Figures 1 and 2,

Figures 4 and 5 illustrate in cross-section and in perspective, respectively, another embodiment of the connecting means between the coupled pistons,

Figures 6 and 7 are similar views of a third embodimeat of said connecting means.

Figure 8 illustrates in detailed cross section the assemblage of the pistons on a shaft, and

Figures 9 and 10 illustrate in longitudinal section and in end view, respectively, an alternative mode of driving of the pump.

As shown in Figures 1 and 2, the pump according to the invention is constituted by a fixed pump-barrel 1 including a cylindrical bore in communication with a suction duct 2 and a delivery duct 3 (Fig. 2). A rotatable cylinder 4 is mounted in the cylindrical bore and is supported by bearings 5, 5 mounted in the end side-plates 6 of the pump-barrel.

The cylinder 4 is cast in one piece and includes two sets of transverse bores 7, 8 and 7, 8; the bores of each set being at right angles to each other and the bores 7',

8' of each set being angularly offset with regard to the bores 7, 8 of the other set- (see Figure 2). In each of these bores are mounted two opposed pistons such. as 9, 9' and 10, 10". (For reasons of clarity, the pistons sliding in the bores 7, 8', are not shown.) The two pistons of each pair such as 10, 10 are interconnected, as shown in Figures 1 to 3, by two fork-shaped pieces 11, 11' and 12, 12', arranged on both sides of the trans verse symmetry plane IIII of the pistons to which these pieces are fixed by means of screws such as 13, 14, 13', 14, 15, 15'. The pistons 9, 9 and 10, 10' of the two conjugated sets are tightened, through a common crossshaped piece or through four independent sole-plates 17, 18, 17', 18 (Figs. 1 and 8) on a bearing 19 or a trun-' nion of a shaft 20, the axis y-y of which is offset with regard to the axis x-x of the rotating cylinder 4. Thus, when the cylinder 4 is set in rotation round the. axis xx, the pistons 9,v 9", and It), 10', are forced to turn round the axis yy, and to reciprocate within the bores 7, 8 of the cylinder, thereby producing suction and discharge of the liquid through the ducts 2 and 3 respectively.

According to the embodiment illustrated in Figures 4 and 5, the coupled pistons 9, 9' and 10, 10' of each pair are interconnected by two pairs of stay-rods 21, 21 and 22, 22' and tightened on the sole-plates 1'7, 1'7 and 18, 18' by means of nuts such as 23, 2 4 and 23, 24.

According to the assembly illustrated in Figures 6 and 7, the pistons 9, 9' and 10, 10 of each pair are interconnected by means of two plates 25, 25 and 26, 26 having in their middle an opening 27, 27 and 28, 28' for the passage therethrough of the shaft 26 and including on their opposite edges a threaded stem 29, 29 extending through a hole 30, 30 in the piston, said hole being enlarged at 31, 31' to receive a lock nut 32, 32" screwed on the threaded stem 28, 28'.

Assembly is easily efiected, no matter which of the described connecting means are used for interconnecting the pistons of each pair 9, 9' or 10, I0, by first introducing the shaft 20 with its bearings or trunnions into the cylinder 4 and assembling afterwards the pistons with their connecting means and introducing them in the transverse bores 7, 8, except that in the embodiment shown in Figures 6 and 7, the connecting plates 25, 26 are introduced in the bores 7, 8 before the insertion of the shaft. In all instances, the connection between the pistons is perfectly rigid and is not subject to deformation. This rigidity of the assemblies of coupled cylinders added to the rigidity of the rotating cylinder cast in one piece allows the pump of the invention to operate under pressures very much greater than the pressures normally used with the rotating piston pumps.

For instance, the pump of the invention permits use of pressures ranging to about 498 pounds per square inch In thepump illustrated in Figure 1, the shaft 20 is fixed to the pump barrel 1, and the pistons are driven by the cylinder 4 which is set in rotation by means of shaft 20' integral with the end portion 4' of cylinder 4 and rotatable in a ball bearing 5" mounted in the side plate 6 of pump-barrel 1, said rotating shaft 20' being eccentricially arranged with respect to thefixed shaft 20.

When the cylinder starts to rotate in the direction of arrow f (counterclockwise) from the position shown in Figure 2, the pistons 9 and 10 are moved back towards the axis of the cylinder 4 thereby increasing the'free space available between the outer surface of said pistons 9 and 10 and the inner surface of pump-barrel 1. Continued rotation establishes communication between the free space of piston 9 and the suction duct 2 with the result that liquid will be drawn in to fill said space. During further rotation, the communication of bore 8 with the suction duct 2 is progressively diminished While communication is progressively established between suction duct 2 with the following bore 7 which is in turn filled with liquid due to the suction effect of the backward motion of piston 10'. After 180 of rotation the piston 9 will have reached its extreme backward position as shown in Figure 2 by piston 9'. From this position the piston is moved outwardly and begins to compress the liquid imprisoned between the piston and the inner surface of barrel 1. As soon as communication is established, during further rotation, between the corresponding bore and the delivery duct 3, the liquid compressed by the outwardly moving piston is expelled under pressure into said duct 3.

Since the rotating cylinder 4 is cast in one piece, it

would be feasible to rotate the pump by means of the shaft 20 which would be mounted to rotate relative to the pump-barrel 1 and not keyed thereto as shown in Figure 1. In this event, the sole plates 17, 18 and the pistons 9 and 10 should be keyed to the shaft 20. But to avoid the transmission of driving torque through the sole-plates 17, 18 and the pistons 9, 10, the invention contemplates, as illustrated in Figures 9 and 10 free mounting of the pistons on the shaft 20, as is shown in Figure l, but to transmit the driving force by means of the offset shaft 20 through pinions keyed to said shaft and meshing with a ring gear provided in the axial bore of the rotatable cylinder 4. As shown in Figures 9 and 10, the shaft 20 is carried, in the side plates '6, 6', by

bearings 33, 33 offset with regard to the bearings 5, 5 which carry the rotatable cylinder 4. The shaft'20 is equipped with two pinions 34, 34' meshing with ring gears 35, 35 provided in the side bosses 36, 36" of the cylinder 4, which is thereby set in rotation in the same direction as the shaft 20 with a reduction ratio depend ing upon the number of teeth in the two sets of meshing gears. This arrangement offers also the advantage of rendering unnecessary, in some cases, the geared speed reducer usually mounted between the driving .motor and the pump.

The operation of the pump shown in Figures 9 and 10 is the same as described in connection with' the pump of Figures 1 and 2.

What I claim is:

Rotating piston pump including a fixed pump-barrel having a cylindrical bore, a suction duct and a delivery duct communicating with said bore, a cylinder cast in one piece mounted for rotation in said bore, at least two transverse bores, crossed at right angles, formed in said cylinder and crossing it right through, a longitudinal bore also provided in said cylinder, an offset shaft arranged in said longitudinal bore and carried by the fixed pump-barrel, two opposed pistons sliding in each transverse bore, two connection pieces arranged on both sides of the transverse symmetry plane of said pistons to which they are removably fixed, means to mount each pair of opposed pistons freely and symmetrically on said offset shaft, a ring gear provided at each end of the longitudinal bore of the rotatable cylinder, two pinions fixed upon the offset shaft and meshing respectively with said ring gears and driving means to rotate said shaft carrying the pinions.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain June 26, 1935 

